Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
It is well known that the polishing of natural stone enhances the aesthetic appeal and value of the stone. Polished marble, granite, terrazzo, etc are expensive building materials but provide a striking and enduring appearance. The polishing of concrete is also known to enhance its value. Specialized machines and equipment have been in production for the polishing of stone and stone floors for over 100 years. Today advanced automated equipment with low cost, advanced and durable diamond tooling make the polishing of stone fast and affordable.
Ceramics for thousands of years have been widely used as decorative, ornamental and construction materials. Because of their strength, durability, ease of manufacture, ease of installation, and relatively low cost, ceramics are frequently the material of choice for floors, walls, panels and pottery. However, there are many instances where it is desirable to have a wall or a surface with a pleasing high gloss finish or shine. It is known in the art that the polishing of fired ceramics has not been possible due to their physical properties.
Typically, to date the only method known to impart a gloss surface onto a ceramic has been through glazing. The method of glazing of ceramic surfaces has been well known for centuries and involves painting a heat activatable glaze onto the article which is subsequently fired to provide a gloss surface.
Although the constituents of kiln fired ceramic are similar to those found in concrete for example, they are present in substantially different proportions. For instance, the main constituent of cement is calcium oxide, typically present in an amount of 61-67% as compared to a typical fired ceramic article like a brick, which contains around 2.8% calcium oxide. Conversely, a brick contains around 66% silicon dioxide which is present in amounts around 23% in cement.
A fired ceramic and concrete also differ in appearance. A ceramic is fired as opposed to concrete which is poured. This imparts a different appearance, however, the major difference lies in the chemistry, since a ceramic becomes an entirely different substance upon firing. During firing, the physical and chemical composition of the constituents of the ceramic are permanently and irreversibly changed. The ceramic constituents undergo a chemical reaction due to the activation and mobility of particles created by the firing process. The chemical reaction created by intense heat of over 1000 degree centigrade enables the formation of a ceramic in contrast to that of concrete which would be totally destroyed by such temperatures. Ceramics are considerably softer and more friable than cement or most other stones and hence the inability to polish them. Ceramics differ intensely from each other largely due to the availability of many different clays mined around the world such as kaolin, fire clay, ball clay, earthen ware and stone ware and the mixture of those clays to form a specific ceramic suitable to manufacture a specific product. Apart from the variations of clays there are many combinations of those clay mixes. The variations are extensive with a large number of fillers added to create a ceramic of a certain colour, density, moisture content, particle size and durability. The vast product range manufactured from kiln fired ceramics includes multitudes of shapes, uses and sizes with seemingly infinite range of designs. All these factors make polishing fired ceramics a much more different proposition than polishing cement or other stones.
Porcelains are a specific and separate form of a fired ceramic with distinct physical properties. The formulation of kaolin, ball clay, ground feldspar, flint and other additives are designed to produce a ceramic with different and specific properties such as hardness, translucency, density and it is a ceramic that absorbs the least amount of water. These are known but their chemistry is different yet again from fired ceramics such as bricks and tiles, and they are also fired at significantly higher temperatures.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.